Closest prior art: the WO 2007/085649 A2 Opposed piston Pulling Rod Engine (OPRE), the U.S. Pat. No. 6,170,443 Opposed Piston Opposed Cylinder engine (OPOC) and the U.S. Pat. No. 1,679,976 Junkers-Doxford engine. Close prior art is also the U.S. Pat. No. 4,732,115 of Lapeyre and the U.S. Pat. No. 4,115,037 of Milton.
The two connecting rods of the OPRE engine are “pulling rods” or “pullrods” in the sense that the high pressure of the combustion chamber loads them exclusively in tension. On the same reasoning the connecting rods of a conventional engine are pushrods.
The pullrod arrangement increases by some 35% (depending on the connecting rod to stroke ratio) the time the piston remains at the last 15% of its stroke near the combustion dead center, i.e. where the injection, the preparation of the fuel mixture, the delay and the most significant and efficient part of the combustion complete. On the same reasoning, when a pullrod engine revs at 35% higher revs than the conventional, it provides to the fuel similar conditions with the conventional.
The U.S. Pat. No. 4,732,115 of Lapeyre necessitates pairs of cylinders and simultaneous combustion at pairs of combustion chambers.
The U.S. Pat. No. 4,115,037 of Milton involves a crankshaft located necessarily at one side of the cylinder.